1961—2008年若尔盖高原湿地的气候变化和突变分析

Climate Variation and Abrupt Change in Wetland of Zoigê Plateau during 1961-2008

利用1961—2008年若尔盖高原湿地境内的5个气象台站的逐月气象数据和玛曲水文站的径流数据,分析了近48a来若尔盖湿地的气候变化趋势,并应用M-K方法、累积距平和滑动t检验对年降水量和平均气温的气候突变进行了检测.结果表明:从1960年代的冷湿期,到1980年代中期到1990年代中后期的冷干期,再到1990年代末起增暖迅速进入暖干期,若尔盖湿地气候呈现较明显的暖干化趋势:一方面,总云量持续减少,日照时数上升,平均气温明显上升,气温日较差逐渐减小;另一方面,降水量、蒸发量、径流量总体都呈减少趋势,干燥指数也逐渐降低.秋季是若尔盖高原湿地气候发生暖干化最明显的季节,气候变暖主要是平均最低温度显著升高的贡献.日较差是蒸发量变化的最重要的影响因子,但低云量、气温、日照等的作用也不能忽视.年平均气温和降水量分别在1997年和1985年发生突变,分别转为迅速增暖和持续减少.

By using the meteorological data of five stations in the Zoige Plateau wetland and the run-off data of Maqu hydrographic station, analyses have been made for seasonal, annual and decadal climate variations as well as the abrupt changes of mean temperature and precipitation. It is found that there was an increasing tendency of warming and drying in Zoige Plateau wetland in the recent 48 years （1961--2008）, especially after the late 1990s. On one hand, total cloud cover have been continually decreased, both sunshine duration and daily temperature range have been increased, and annual mean surface air temperature have been risen with a warming rate of about 0. 17℃. （10a）^-1 .On the other hand, precipitation, evaporation, and runoff have been decreased in the last 48 years. Of the four seasons, autumn experienced the most obvious warming and drying, spring, less obvious. Daily temperature range was the most significant impact factors of the evaporation, but low cloud cover, temperature, and sunshine duration were also important. Finally, detections of climatic abruptness are made on annual mean temperature and annual precipitation by three means, and the years 1997 and 1985 are hence respectively checked out as the abrupt change points of mean temperature and precipitation.